Thoughts on teaching biology

Tag Archives: evolution

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One thing to note, it has taken a long time for a vaccine resistant strain to show up. Vaccines don’t act as selection pressures in the same manner that antibiotics and antivirals do. Antibiotics act as immediate threats to survival, selecting for the mutants in a population that can survive in the presence of an antibiotic. Vaccines functionally increase the number of infectious particles needed to overcome immunity.

Think of it this way, once you start a course of antibiotics, you already have billions upon billions of pertussis bacteria playing pinochle in your snout, pleural cavity (where your lungs are) and elsewhere, and you have probably exposed everybody that lives with you and a majority of people that work or go to school with you. If they have not been vaccinated, or have not received a booster in the last decade or so, they will be infected.

If a person has been vaccinated and has strong immunity from the vaccine, only the bacteria that are already mutated in a manner to evade the vaccine have much of a chance of successfully starting an infection. Some bacteria are better than others at infecting a host, and a smaller number of bacteria are needed to kick off an infection. This is called an infectious dose. The infectious dose of pertussis is probably pretty low, since it is so easily transmitted (susceptible coworkers are 70-90% likely to catch whooping cough, and since kids have terrible hygiene, its even higher for them. Since we don’t know what that dose is, let’s just call it X. If the mutation to evade a vaccine is only present in one out of a million bacteria (a very generous guess), the infectious dose for a vaccinated individual is one million times X. This makes it a lot harder for a vaccine evading strain of a bacteria like pertussis to get started than an antibiotic resistant strain. Luckily, when antibiotic resistant strains show up, they don’t tend to spread very well, probably because the level of vaccination is decently high.

Continuing as a cat / non-cat accommodationist, how far apart are nudibranches (the specific one shown munching away at a Portuguese man o’ war in the video is a blue dragon, Glaucus atlanticus) and housecats (Felis catus / Felis domesticus)? This is a painful one. They are very far apart, as one would expect for members of different phylums.

I’m concerned that this cat / not cat is driving us away from what should be our real focus, which is that we shouldn’t trust those weird prokaryotes. No nucleus, no way. Cats have cells with nuclei, which is fine by me.

Right. I’ll get to the science stuff in a minute. There’s a meteorite that hit the ground near here. I want to check it out. It won’t take long.

If you are teaching an astronomy class, I have a challenge for you. Introduce your students to minority astronomers. Neil deGrasse Tyson isn’t the only black astronomer! When I teach introductory biology I make sure to teach about women that are scientists and at the end of the semester, I often give a bonus point on the final if students can name a single female scientist that isn’t Marie Curie. Some can, some can’t.

Via Boing Boing, a heartwarming discussion of how your bellybutton is a special place for bacteria. OK, so it isn’t heartwarming, but what class from high school biology on up doesn’t involve sampling skin bacteria and growing them on petri dishes. It becomes slightly more intensive when you get into actually identifying all the bacteria present, but this is probably something that upper level courses might consider, if they have the required technology and resources.

Speaking of bacteria, and why not, since we are just walking, talking bacteria hosts and vectors, is this neat little bit on how certain bacteria have distinct smells. A well stocked lab with good safety controls could easily show off some of these lovely little bugs and remind students to use all their senses when making observations.

This piece actually reminds me of something I came across years ago about the naming of several short chain fatty acids (which happened to tie into my dissertation, another story for another day) and guess what, thank the interwebs, it still exists! If you are teaching a primary, secondary or introductory chemistry course, this would be a neat little thing to toss into a lab. It would only take a few minutes, perhaps while something else is going on, but having some samplers of things like butyric acid and a bit of rancid butter to compare it with would be a neat sensory lab. I’m not sure how you get a goat to compare caproic (hexanoic) acid with, but maybe some goat hair would do?

Worrying response to fatal shark attacks off the coast of Australia. While five fatal attacks in ten months sounds like it should be a definite concern, is it a trend marking a change in behavior? I’m not so sure.

If you look at the number of fatal attacks for all of Australia for the last decade, there is no clear trend that can be discerned. It is highly disturbing that there are now calls for a hunt for the shark responsible for the most recent attack. Attempting to hunt down the one large great white shark in an ocean that attacked a person is simply not a feasible idea. Great white sharks can roam dozens of miles in a day and can migrate thousands of miles seasonally. Without clear identification of the shark, checking stomach contents of a killed shark would be the only way to determine if you had caught and killed the right shark.

Revenge hunts won’t convince other sharks not to attack. People watching for sharks in the vicinity of beaches is a good preventative, but is not any more functional with a long coastline.

Tara C. Smith describes using zombies to teach about diseases, pandemics and other public health issues. How cool is that? What an excellent opportunity for discussion and fostering an active learning environment!

More joy from the Philipines, sea turtles saved from poacher’s nets. This probably should be viewed in the context of a larger dispute over territorial waters claimed by both China (where the poachers were from) and the Philipines, as noted in the link.

Apparently moon dust is bad for you. Well, I could have told you that! Sharp pieces of regolith could get in your eyes and scratch your cornea or irritate your airways, not unlike inhaling ground glass. Here is the paper for specifics.

E. coli strain 0157 is a very nasty bug, and since there is no good reason to assume that the Germantown, Ohio outbreak came from meat (a recent outbreak was linked to feral hogs foraging in fields being used to produce vegetables), it will be interesting to see if a source is found. I’ll be keeping my eyes on the MMWR. In fact, students in any microbiology, disease ecology or public health course dealing with epidemiology should be asked to read and present reports from the MMWR as part of their course in order to see how the things they are studying are reflected in the real world.

There is a belief that lies can be detected via body language hint of looking up to the left. Apparently (surprise), it isn’t true, or at least is unreliable. Just like so many other liedetection tools.

The placebo effect is a very important concept to understand when examining any claim that a drug, intervention, device, whatever, has a positive effect. Well designed clinical trials can help researchers separate false effects from real ones (which is why alternative medicine seems powerful in small trials with poor statistical power, but when examined in large randomized double blind trials, the effect is no different from placebo. Hope plus effective treatment is very powerful. Hope plus nothing may make a person feel good in the short term, but in the long run can lead to dangerous delays in treatment.

People are less familiar with the nocebo effect, wherein something has a negative effect, even if there is nothing there.

In one study, 44 percent of lactose-intolerant people reported gastrointestinal problems after taking a fake lactose tablet. (Impressively, a quarter of people without lactose intolerance also reported digestive troubles after taking the tablet.) And in a somewhat cruel prostate drug study, one group of subjects was told that sexual dysfunction was a possible side effect, while the other group wasn’t. The better-informed group reported sexual side effects at a rate of 44 percent, compared to only 15 percent in the blissfully ignorant group.

People can actually make themselves more likely to experience side effects by simply knowing about them. Medical and nursing students would be well served by reading and discussing how this affects their interactions with patients and communicating risks of treatments. There is a fine line between communicating and providing informed consent and negatively influencing a patient’s treatment.

Undergraduate students in psychology or communication courses would also benefit from class discussions about interactions and how they affect both patient expectations and patient compliance (the linchpin of slowing the development and spread of antibiotic resistance).

It can be difficult to express the sheer diversity of ferns, but this SA blog post does that in spades. Don’t just show your students a fern from the florist. Show them the wild variety of these ancient plants and toss in some examples of ferns from the fossil record. If you can afford it, add some to your personal or department fossil collection.

Mixing live virus vaccines that can mix genes is causing problems in chicken farms. Could this happen in humans? Except for the oral polio vaccine, no, because our live virus vaccines that are given simultaneously can’t mix genes. The oral polio vaccine can recombine, but this is uncommon, and the oral vaccine is only used where polio is still a common disease. Is this virus a risk to people? No, people can’t catch this particular virus. If this sounds like the flu strains swapping genes, it should.

I love cats and cats go so well with science. Cats aren’t just something that students are familiar with, but they have some great features that make them good teaching tools. For example, calico and tortoiseshell cats are almost always female because the mix of alleles that cause a tricolor cat can only occur in a cat with two X chromosomes. A male cat that is calico is going to be the feline equivalent of Klinefelter’s syndrome. If it is as common in cats as it is in people, an assumption for which I have absolutely no evidence, then only 1 in 500 to 1 in 1000 male cats would be feline Klinefelter’s, even before the color pattern is determined.

So why are calico cats important? Find me an introductory biology text that doesn’t have a picture of a tricolor cat in the section about X chromosome interaction. They give us a visible examples of the mosaics formed during development as one X chromosome or another is inactivated, and only the color gene on the active chromosome is expressed. The presence of two active X chromosomes in a cell is probably toxic on some level to the animal. This likely has to do with the effect that the dosage of genes on a single chromosome being just right, while two is too much. More on cats in the classroom and the effects of aneuploidy on cells in the future, just not simultaneously.

Gorgeous video of a variety of insects getting a tasty, nutrient rich snack of pollen. Don’t worry, the flower will probably benefit by having a little bit (just enough) pollen finding its way to a stigma and then on to an ovary. (via @BugGirl on the twitter machines)

Auroras are pretty neat. Maybe I’ll get a chance to see one some time. I just hope it doesn’t come with a solar flare powerful enough to be visible in Central Kentucky. Phil Plait not only has coverage of the most recent flare, but like he suggests, check out his related links for far more information than I could possibly impart. Just don’t forget to enjoy this video of the aurora from the BBC.

Geologists in Peru are working to preserve a 3.6 million year old “whale cemetery” containing at least 15, probably more fossil whales killed by a volcanic ashfall. Most of the preservation work will be to prevent erosion of the fossils due to exposure to harsh wind driven sand.

Fascinating examination of a fossil bird showing traces of various elements left over by the mineralization process. The copper present is likely to be from the eumelanin pigment, giving hints regarding the color pattern of this 120 million year old bird.

A fossil of an early bird egg has been found (these are pretty rare, apparently) and is shaped like a modern oval egg. This is similar to the egg shape of the therapod dinosaurs, from which it is thought that birds evolved.

I find myself wishing a case of diptheria on the people that destroyed a hadrosaur fossil at an Alberta dig site. Apparently, some idiots have made a habit of destroying the fossils while drinking. Don’t do that.

The HPV vaccine may already be having an effect on herd immunity, with infection rates dropping in unvaccinated groups.

REM sleep behavior is one of my favorite sleep disorders, since I have yet to find any suggested link between it and the paranormal. Sleepwalking, night terrors, sleep paralysis… they all get blamed on ghosts, ghoulies, and aliens, but not this one. And it seems to have some link to neurodegenerative disorders in a majority of the cases.

Bicycling is fun, and I don’t get to do it nearly as much as I would like to… but knowing how to fit your bike properly is important. In fact, it can affect your sexual health.

What happens if you “get spaced” or “cold shirt it?” Your vacuum questions answered here. (I regularly get asked this one by students. It feels good to be right.

Genetics

Are we teaching genetics properly? Are we bogged down in the history of the science so much that we ignore the state of the art? It is beginning to look like it. If you are as interested in evidence based teaching as much as I am, you should read this and the paper that goes with it. Better course design = better courses.

Zoology

I’m sure you have seen this by now, but a shark stole this young woman’s fish! But did you immediately know what shark it was? Bull sharks swim upriver, in fresh water, for as much as hundreds of miles, so being in a coastal wetland is nothing out the ordinary.

Just the other day, I thought I heard cicadas. I did! I did! Brood I is out, and despite being in an area that has had almost all of its old trees removed and replaced with young trees, I was surprised to hear any at all. Cicadas live underground on tree roots for so long that removing the trees can put a real kink in their reproductive cycle. Go and see the great video at Bug Girl’s place.

Evolution

“What Darwin Didn’t Know” is a pretty good documentary on evolution and is now available online. Check it out.

The demise of evolution in the textbooks of South Korea was wildly incorrect. A short piece in one book that was scientifically incorrect was removed and is going to be updated. This was trumpeted in the world media as a complete removal of evolution… and nobody checked the sources. Always check your sources.

Botany

A new species of plant in the British Isles has been discovered. It resulted from the hybridization of two related invasive species, and is significant because speciation in the wild is not something we usually get to observe.

Excellent video on global warming / anthropogenic climate change. Not too long to use up a whole class period, but a good way to start discussion.

If we cut our CO2 levels now, will the oceans stop rising? Yeah, not so much. There is lag time between CO2 release and the effects that it has on climate.

Overexploitation of natural resources such as fisheries is a major problem for the environment. 30% of fish stocks are overexpoited, which will make it more and more difficult to make a living from fishing and can drive species to the brink of extinction, if not right over the edge.

Is the current batch of extreme weather events due to global warming / antropogenic climate change? We have to be careful making statements regarding this. Weather isn’t climate. Short term events are not long term trends. So, what we really need to do is take a look at what has been predicted based on climate models. Does this fit with those predictions? Yes. Is it likely due to global warming? Very likely. Should we be careful in our phrasing and how we talk about climate’s relationship with weather? Absolutely (although I think MarkCC is a bit hard on Phil). Sad thing is, nuanced discussion doesn’t go over with the media very well and is weak in the face of a lie told with certainty.

Why do non-Newtonian fluids act like they do? Physics. Its like three dimensional chain mail, becoming rigid under impact, The suspended particles are pressed together and form a structure that resists the pressure. Make some ooblek, play with it, teach.

Lots of tidbits, lots of links, enough to make a few tidbytes, even (8 tidbits = 1 tidbyte).

Feathers may have been an early adaptation, perhaps even basal, of Saurischian dinosaurs (which includes therapod dinosaurs), appearing so early in the evolutionary tree that many therapod dinosaurs (if not most) may have had feathers. Saurischian dinosaurs are one of the two major orders of dinosaurs, the other being Ornithischia, both named for the structure of their pelvic bones. Saurischian dinos have a lizard like hipbone, while Ornithischia has a bird like hipbone. Interestingly, it is the Saurischian group that is thought to have given rise to birds.

What kind of feathers, though? There are eight feather types that are documented within modern and extinct birds, all the way back to feathered dinosaurs.

Feather evolution was broken down into the following stages by Xu and Guo in 2009:

Single filament

Multiple filaments joined at their base

Multiple filaments joined at their base to a central filament

Multiple filaments along the length of a central filament

Multiple filaments arising from the edge of a membranous structure

Pennaceous feather with vane of barbs and barbules and central rachis

Pennaceous feather with an asymmetrical rachis

Undifferentiated vane with central rachis

However, Foth (2011) showed that some of these purported stages (stages 2 and 5 in particular) are likely simply artifacts of preservation caused by the way fossil feathers are crushed and the feather remains or imprints are preserved. Foth re-interpreted stage 2 feathers as crushed or misidentified feathers of at least stage 3, and stage 5 feathers as crushed stage 6 feathers.

Modern birds have feather types 4, 6, 7 and 8 (chicks have filament feathers similar to type 1). The dinosaur that is the subject of the research paper that sciencenews is presenting a press release on a 150 million year old fossil of Sciurumimus albersdoerferi, which has type 1 feathers. A dino covered with type 1 feathers would have looked kind of fuzzy, like a kiwi. Not the fruit, the bird. This supports other evidence for feathered dinosaurs in the therapod group existing as far back as 160 million years ago. Therapods are the dinosaurs come to mind when you think of Tyranosaurs or Velociraptors.

What I am most interested in is that feathers are made of a protein called keratin. Keratin is the waterproof filamentous protein that makes up the outer layer of your skin, hair and nails. Keratin is also present, in one form or another, in all vertebrates. Hooves, horns (like those of a rhino) and baleen are all also made of keratin. Amphibians produce keratin, but only on their feet and perhaps belly, as protection against abrasion, while lizards, snakes and all other reptiles produce keratin all over their skin, and it is one of the major evolutionary adaptations that let reptiles live away from water. Carl Zimmer, one of my personal science journalism heroes, has an article at NatGeo on the evolution of feathers, as well as the evolution of our understanding of the evolution of feathers. I highly recommend reading it and passing it along to interested students of all levels.

Depending on how and where they are expressed, they can make up very different structures, which is one of the primary concepts within evolution. Inventing the wheel is quite easy when the parts you need are already present and only need a modification here and an alteration there. With minor mutations here and expression changes there, scales become modified into feathers, which become altered into more complex feathers with further mutations, each becoming useful for different purposes. And all of this from one group of proteins with incredible versatility.

CERN is getting ready to tell couldn’t take the excitement and told us something about the Higgs boson. Great fun for physicists. I have no clue what it means. Dammit, I’m a doctor (biologist), not a doctor (particle physicist)! Luckily, there are people that can explain it.

BoingBoing has a great article up as a piece on cell division and embryogenesis in sea urchins. The videos there would make for great media pieces in the multimodal classroom.

You can learn a lot from fossils, even fossil poop. Yeah, sometimes, feces fossilize (and are called coprolites), and we can learn about the diet of the animal that produced it. In this case, the New Zealand Moa’s coprolites have been examined, and these exceptionally large flightless birds ate plants, and don’t seem to have been too picky. This can relate to the classroom quite easily in any lab where students examine owl pellets. This is a very similar experiment in some ways, examining the contents, but without the carbon dating and DNA analysis.

What drove the moa to extinction around 1500 CE? Humans arrived on the island before this point, and apparently moa were delicious. If only they had survived, I could have a 12 piece New Zealand Fried Moa bucket.

Eugenie Scott of the NCSE talking at the Global Atheist Convention 2012, via Token Skeptic. This talk has some great pearls of knowledge for regarding creationist attempts to do science, and how they don’t mesh with the evidence. (evidence they conveniently ignore)

I love parasites. They are seriously cool. For every animal that feeds itself, there is an animal that lives off of it as a parasite. Some of those parasites have parasites of their own.

The smallest of ants were thought to be safe from phorid flies, a parasite that lays eggs in the heads of ants. The larva emerges, eats the goodies in the ant’s head, and when it is ready to emerge as an adult fly, the head falls off and the fly comes out.

Well, size doesn’t matter to a newly described species of fly that is smaller (0.4 mm long) than any previously described member of the family. So far, the researchers have no idea what the host of this tiny parasite is, but you can be sure they are looking.

In any discussion of how organisms gain their food, parasitism comes up, and visceral examples like this fly can be very interesting to students.

They don’t have mouths. They don’t have stomachs, intestines or anuses either, and yet, they eat the bones of dead whales, and are called bone eating worms or osedax, which means bone eating in Latin.

They use a branching anchor with rootlike structures, covered in microvilli, to secrete acid, which breaks down the calcium structure, liberating fats, which are absorbed and then digested by bacteria living in the tissues of the worm. And zombie worms aren’t even the most grossly named of these critters. Behold the bone eating snot flower worm!

So they don’t eat, but do break down bone and absorb food from their surroundings.

It sounds a bit like a fungus, actually. And this can be a great chance for you to talk about how what a normal defining characteristic of a kingdom (ingesting food for Animalia, photosynthesis for Plantae) are sometimes abandoned, but the organism never hops to another kingdom. A ghost orchid that doesn’t photosynthesize is still a plant, existing as a parasite on fungi underground, only poking up to flower on rare occasion. Students often want to think of non-photosynthesizing plants as fungi, and might want to do the same with bone eating worms, but they still have all the other features of their kingdoms. The osedax still doesn’t have cell walls or mycorrhizaelike a fungus. It still has closer genetic ties to other polychaetes and annelids than to anything else. The ghost orchid still has cellulose cell walls instead of chitin. It may not have chloroplasts, but it still is a plant. Great chance to have a lesson on phylogenetic trees.

Another topic you can bring up is the use it or lose it concept. Osedax don’t use a digestive tract and don’t need one. The genes for a digestive tract are turned off and over the millions of years since they evolved, the genes probably have become mutated into a non-functional state. It was once assumed that once you go down this tract, you can’t go back, but scientists have found that geckos have gained and lost their adhesive toe pads several times, and some lineages of scorpions have gone from surface to cave dwelling and back, and lost their eyesight and regained it. The longer you don’t use something and it remains unexpressed, the harder it is to reactivate, but it isn’t impossible.

I would really love to see a study of the early development of these worms, especially to see if their larval forms have digestive tracts.

One other cool detail… Osedax have both male and female sexes, but the males live in a larva like state inside the female.

Worms = cool

A new gene in the influenza virus has been discovered. Let me pick up my teeth. Influenza just went from a genome of 10-11 genes to 11-12.

The gene is hidden in the code of another gene, and it appears to limit the severity of the immune response. If the mouse model is correct, when this gene works, the flu symptoms are less severe. If it is mutated, the flu is more severe and is more likely to kill otherwise healthy people.

The gene wasn’t discovered until now because it is found after the main gene on segment three starts. It basically is a second open reading frame (this is the link to the original paper in the journal Science), and is activated by a ribosomal frame shift. (Does this sound like it may be for an undergraduate genetics course? Oh yeah. But don’t be afraid of handing it to a gifted high school student.)

Basically, the gene is transcribed as normal, making the viral mRNA. The mRNA is then translated, and when the ribosome reaches the start of the internal gene, it slips, missing a nucleotide and the rest of the protein is produced according to the internal gene. This is similar to eukaryotic alternative splicing, and is a very cool way to get two genes coded into the space of one.

This produces a protein that represses the genes of the cell, and probably inhibits the cell from putting up the little red flags that tell the immune system that it has been infected. Less immune response, less chance for a cytokine storm, the nightmare scenario for flu.

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I am a toxicologist/cell biologist, and am preparing a downloadable study guide for biology students, as well as teach at Georgetown College as needed. The views expressed here are my own and do not reflect the views or opinions of Georgetown College. My love of teaching and interest in sharing ideas on how to approach topics in science education are why I have returned to blogging.

I am not anti-Christian as creationism is not the only view accepted by Christians nor is it a solely Christian belief.

If you want to contact me on a specific topic, leave a comment. I am available for talks on the importance of science education and literacy and various other science and critical thinking topics.

I will not debate individuals from anti-science groups as I feel this gives undeserved legitimacy to their beliefs that cannot be obtained via publishing in quality peer reviewed journals.